Place coconut in pan; cook, stirring, over a low fire, until golden brown. Cool for 5 minutes. Set aside.

Process onions, ginger, garlic, lemon grass, chili flakes and water in an electric blender to form a paste.

Combine beef, spice paste, coconut milk, extra water, salt and sugar in a large pan. Bring to the boil; than simmer, uncovered, stirring occasionally, for about 2 hours, or until most of the liquid has evaporated.

Add reserved coconut, lime leaves and lemon juice. Cook, stirring constantly, over a low fire for a further 20 minutes.